Along with the popularization of terminal equipment such as fixed telephones and mobile phones, the terminal equipment have greatly facilitated people's work and living in the way that people may communicate with others through terminal equipment at any time. However, terminal equipment also bring some troubles to their users. For example, a user does not want to be disturbed by unimportant phone calls at night or during leisure time, but he also does not want to miss important calls. However, in fact there are unimportant calls coming in during such periods, some of which are even harassing calls.
The user may turn off the terminal equipment to avoid being disturbed by unwanted calls and turn on the terminals again when he needs them. Terminal equipment comprises fixed terminals and mobile terminals, and it is comparatively easy to turn off the mobile terminals. However, the only way to turn off a fixed phone is to disconnect the telephone line, which is very inconvenient for the user. Moreover, turning off terminals, mobile or fixed, will bring other problems: the user will not get any phone calls when the terminal equipment is turned off, and others will not be able to contact the user even with very important business matters. And the user needs to turn on the terminals again when he needs them. It is convenient to turn off or turn on the mobile terminals, but the user commonly forgets to turn on fixed terminals. Thus the user will not get the phone calls from anyone through the terminal if it is not turned back on.
The user may also utilize the secretary service currently offered by the mobile communication system, but the service is applied to the mobile terminals only. The user of the mobile terminals may customize the settings of his secretary station; for instance, the user who does not want to be disturbed by the phone calls may require the secretary station to record voice messages for the calling users and send the messages to the user. Therefore when the secretary receives the phone call for the user, it will ask the calling user to leave the message and then inform the called user by short messages or other means. The called user calls the secretary station to get the voice message left for him by the calling user. The called user may decide whether to call back according to the content of the voice message, and thus will not be disturbed by incoming calls.
However, the secretary service is a paid service, i.e. the users of the service need to pay for it. The secretary station only converts incoming calls into short messages or other forms of notices to the called user, so the called user still receives short messages or other messages instead of calls and will still be disturbed. So this solution is not a perfect one. Besides, the short messages from the secretary station to the called user may be delayed or even lost, and the called user may not read the short messages in time. For example, the short messages are not real-time communication and the users usually set gentle, weak or even mute short message notification sounds, so it is usual for a user to fail to handle the short messages in time and accordingly fail to handle the urgent business in time.
Another solution is to set an incoming call filter. For instance, blacklists and whitelists can be used to protect users from the disturbance of unimportant phone calls while guaranteeing that important calls will never be missed. For instance, the whitelist solution comprises: setting a whitelist of calling numbers that are allowed to access the called terminal; when the called terminal enables the whitelist function, only the calling numbers in the whitelist may access the called terminal. The whitelist solution may solve the above-mentioned problem to a large extent, but the authorized calling numbers are limited in the solution. When a user A needs to call a user C in an emergency, supposing that the cell phone number of the user A is in the whitelist, but the user A calls with a user B's cell phone, the number of which is not in the whitelist, when his own one is out of power, the user A is unable to call through a number in the whitelist so that the user A will not be able to contact user C. The blacklist solution comprises: setting a blacklist of calling numbers that are not allowed to access the called terminal, when the called terminal enables the blacklist function, the incoming calls from the numbers in the blacklist will be refused. The blacklist solution is unable to refuse incoming calls from the number outside the blacklist. For example, harassing calls from public telephones are not refused in the blacklist solution. What's more, the maintenance of the blacklist and the whitelist is complicated.